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This disclosure relates to a waste heat recovery (WHR) system and to a system and method for regulation of a fluid inventory in a condenser and a receiver of a Rankine cycle WHR system. Such regulation includes the ability to regulate the pressure in a WHR system to control cavitation and energy conversion.
This disclosure relates to a waste heat recovery (WHR) system and to a system and method for regulation of a fluid inventory in a condenser and a receiver of a Rankine cycle WHR system. Such regulation includes the ability to regulate the pressure in a WHR system to control cavitation and energy conversion.
Rapid growth in scientific data and a widening gap between computational speed and I/O bandwidth make it increasingly infeasible to store and share all data produced by scientific simulations. Instead, we need methods for reducing data volumes: ideally, methods that can scale data volumes adaptively so as to enable negotiation of performance and fidelity tradeoffs in different situations. Multigrid-based hierarchical data representations hold promise as a solution to this problem, allowing for flexible conversion between different fidelities so that, for example, data can be created at high fidelity and then transferred or stored at lower fidelity via logically simple and mathematically sound operations. However, the effective use of such representations has been hindered until now by the relatively high costs of creating, accessing, reducing, and otherwise operating on such representations. We describe here highly optimized data refactoring kernels for GPU accelerators that enable efficient creation and manipulation of data in multigrid-based hierarchical forms. We demonstrate that our optimized design can achieve up to 250 TB/s aggregated data refactoring throughput—83% of theoretical peak—on 1024 nodes of the Summit supercomputer. We showcase our optimized design by applying it to a large-scale scientific visualization workflow and the MGARD lossy compression software.
This review article reports an overview of the recent developments in the field of electron delocalization study in organic conjugated molecules by utilizing the vibration frequencies exhibited by the attached functional groups such as nitrile (–C≡N), alkyne (–C≡C–), or carbonyl (–C=O). A brief introduction to electron delocalization, methods for study, and their importance is given first, followed by the application of infrared spectroscopy in organic molecules. Details of molecules with various infrared reporter groups have been explained in respective subsections based on the functional groups. All the reported organic molecules have been structured and presented with the electron delocalization properties studied using an infrared reporter group. Finally, an outlook on this recently promising, exciting, and interesting field of probing electron delocalization using infrared reporter groups is provided.
The objective of this paper is to improve the power conversion efficiency of HIT solar cell using amorphous materials. A high efficiency amorphous material based on two dimensional heterojunction solar cell with thin intrinsic layer is designed and simulated at the research level using Synopsys/RSOFT-Solar Cell utility. The HIT structure composed of TCO/a-Si:H(p)/a-Si:H(i)/c-Si(n)/a-Si:H(i)/a-Si:H(n{sup +})/Ag is created by using of RSOFT CAD. Optical characterization of the cell is performed by Diffract MOD model based on RCWA (rigorous coupled wave analysis) algorithm. Electrical characterization of the cell is done by Solar cell utility using based on Ideal diode method. In addition, optimization of the different layer thickness in the HIT structure is executed to improve the absorption and thereby the photocurrent density. The proposed HIT solar cell structure resulted in an open circuit voltage of 0.751 V, a short circuit current density of 36.37 mA/cm{sup 2} and fill factor of 85.37% contributing to the total power conversion efficiency of 25.91% under AM1.5G. Simulation results showed that the power conversion efficiency is improved by 1.21% as compared to the reference HIT solar cell. This improvement in high efficiency is due to reduction of resistive losses, recombination losses at the hetero junction interface between intrinsic a-Si and c-Si, and optimization of the thicknesses in a-Si and c-Si layers.
Sugarcane is being enhanced as a bioenergy crop by engineering it to accumulate and store lipids along with polymeric sugars in vegetative tissues. However, there is no existing process that allows for processing this new crop to recover both lipid and cellulosic sugars from the oilcane bagasse. Therefore, a comprehensive investigation of two pretreatment methods—natural deep eutectic solvents (NADES) and chemical-free hydrothermal pretreatment (HT) was conducted to judge their suitability for recovering fermentable sugars, lipids, and lignin from bagasse. Two NADES, i.e., choline chloride: lactic acid (ChCl:LA) and betaine: lactic acid (BT:LA) were prepared using a 1:2 M ratio and were evaluated for pretreatment of oilcane bagasse at 10, 20, and 50 % (w/w) solids, followed by enzymatic hydrolysis at 10 % (w/w) solids. Notably, ChCl:LA NADES treatment at 10 % (w/w) solids at 140 °C for 2 h, solubilized 78.8 % of lignin and 80.4 % of hemicellulose and allowed 82.7 % enzymatic conversion of glucans to glucose. In contrast, HT pretreatment removed approximately 87.6 % of the hemicellulose and provided an enzymatic glucose yield of 69.7 %. Furthermore, ChCl:LA operated at 50 % solids loading the enriched lipids 2.6-fold (9.2 wt%) in recovered solids compared to HT (6.4 %) and BT:LA (5.1 %) pretreatment processes. NMR-HSQC and GPC analysis showed that ChCl:LA also cleaved the most lignin β–O–4 linkages and demonstrated lower molecular weight compared to HT. This study demonstrates that NADES pretreatment is an effective green processing method for recovering lipids, sugars, and lignin from bioenergy crops at high solid loading (50 % w/w) within the context of an integrated biorefinery.
Presented is an experimental study on catalytic conversion of carbon dioxide into methanol, ethanol and acetic acid. Catalysts having different catalytic functions were synthesized and combined in different ways to enhance selectivity to desired products. The combined catalyst system possessed the following functions: methanol synthesis, Fischer-Tropsch synthesis, water-gas-shift and hydrogenation. Results showed that the methods of integrating these catalytic functions played important role in achieving desired product selectivity. It was speculated that if methanol synthesis sites were located adjacent to the C-C chain growth sites, the formation rate of C2 oxygenates would be enhanced. The advantage of using high temperature methanol catalyst PdZnAl in the combined catalyst system was demonstrated. In the presence of PdZnAl catalyst, the combined catalyst system was stable at temperature of 380oC. It was observed that, at high temperature, kinetics favored oxygenate formation. Results implied that the process can be intensified by operating at high temperature using Pd-based methanol synthesis catalyst. Steam reforming of the byproduct organics was demonstrated as a means to provide supplemental hydrogen. Preliminary process design, simulation, and economic analysis of the proposed CO2 conversion process were carried out. Economic analysis indicates how ethanol production cost was affected by the price of CO2 and hydrogen.
Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecular-level thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst-support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free high-performance and durable alkaline fuel cells and related technologies.
The sustainability of the biofuel industry depends on the development of a mature conversion technology on a national level that can take advantage of the economies of scale: the nth-plant. Defining the future location and supply logistics of conversion plants is imperative to ultimately transform the nation’s renewable biomass resources into cost-competitive, high-performance feedstock for production of biofuels and bioproducts. Since the US has put restrictions on production levels of conventional biofuels from edible resources, the nation needs to plan for the widespread accessibility and development of the cellulosic biofuel scenario. Conventional feedstock supply systems will be unable to handle cellulosic biomass nationwide, making it essential to expand the industry with an advanced feedstock supply system incorporating a distributed network of preprocessing depots and conversion plants, or biorefineries. Current studies are mostly limited to designing supply systems for specific regions of the country. We developed a national database with potential locations for depots and biorefineries to meet the nation’s target demand of cellulosic biofuel. Blended feedstock with switchgrass and corn stover (harvested by either a two- or three-pass method) are considered in a Mixed Integer Linear Programming model to deliver on-spec biomass that considers both, a desired quantity and quality at the biorefinery. A total delivered feedstock cost that is less than $79.07/dt (2016$) is evaluated for years 2022, 2030, and 2040. In 2022, 124 depots and 59 biorefineries could be supplied with 42.8 million dt of corn stover and switchgrass. In 2030 and 2040, the total accessible biomass could increase to 215% and 393% respectively when compared to 2022. However, an $8/dry tons reduction in targeted delivery cost could reduce total accessible biomass by 67%. Kansas, Nebraska, South Dakota and Texas were identified as potential states with a strong biofuel economy given that they had six or more biorefineries located in all scenarios. In some scenarios, Colorado, Alabama, Georgia, Minnesota, Mississippi and South Carolina would greatly benefit from a depot network as these could only deliver to a biorefinery in a nearby state. To elaborate the impact of a nationwide consideration, the findings were compared with existing literature for different US regions. We also present results for biorefinery capacities that are double, triple, and quadruple in size.
Ammonia (NH3) has garnered significant interest as an alternative fuel for meeting international emissions reduction mandates in sectors with high weight and distance requirements, such as shipping. Technical barriers and unanswered questions remain on the combustion strategies that can maximize ammonia utilization and minimize emissions. Prior research studies at the US Department of Energy’s Oak Ridge National Laboratory have shown strong performance with NH3 under dual-fuel mode using conventional diesel combustion (CDC) manifold air pressure settings. Diesel airflow was initially used to simplify retrofitting (no turbocharger modification), which resulted in air-fuel equivalence ratios (λ) greater than 1.5. To characterize potential improvements in dual-fuel NH3 combustion performance at richer in-cylinder conditions, a global λ sweep compared the use of early (E-pilot) and late (L-pilot) single diesel injections. The experiments were conducted at 1200 RPM and 12.8 ± 0.2 bar (75 % load), and λ was varied by decreasing the commanded air flow to the engine at greater than 90 % ammonia energy substitution level. A diesel injection timing sweep was conducted for both the injection strategies at fixed λ, and the timing with the lowest engine-out N2O emissions was identified. The results indicated an optimal balance between CO2,eq and thermal efficiency benefits both E-pilot and L-pilot injection strategy cases compared with CDC at a λ of 1.4. The indicated nitrogen-based emissions exhibited a strong correlation to the ratio of CA5–50 and ignition delay for L-pilot, but no apparent trend emerged for the E-pilot injection strategy at the tested boundary conditions. This dataset includes the raw experimental data and documentation of the experiment conditions and methods.
The overall objective of this project was to develop multiscale models for understanding and eventually designing complex processes for renewables. To the best of our knowledge, our work is the first attempt at modeling complex reacting systems, whose performance relies on underlying multiscale mathematics and developing rigorous mathematical techniques and computational algorithms to study such models. Our specific application lies at the heart of biofuels initiatives of DOE and entails modeling of catalytic systems, to enable economic, environmentally benign, and efficient conversion of biomass into either hydrogen or valuable chemicals.
The present invention relates to a protonic ceramic fuel cell and a method of making the same. More specifically, the method relates to a cost-effective route which utilizes a single moderate-temperature (less than or equal to about 1400° C.) sintering step to achieve the sandwich structure of a PCFC single cell (dense electrolyte, porous anode, and porous cathode bone). The PCFC layers are stably connected together by the intergrowth of proton conducting ceramic phases. The resulted PCFC single cell exhibits excellent performance (about 450 mW/cm2 at about 500° C.) and stability (greater than about 50 days) at intermediate temperatures (less than or equal to about 600° C.). The present invention also relates to a two step method for forming a PCFC, and the resulting PCFC.
Methods for producing non-platinum group metal electrocatalysts effective for the reduction of oxygen in fuel cells and other electrochemical reactions and electrocatalysts as may be produced by these methods are described. The electrocatalysts can be formed according to low to medium temperature formation methods and may be particularly attractive for use in low-temperature fuel cells.
An in-situ method to measure changes in catalyst particle size at the cathode of a proton exchange membrane fuel cell is demonstrated. Synchrotron X-rays, 58 keV, were used to measure the pair distribution function on an operating fuel cell and observe the growth of catalyst particles under accelerated degradation conditions. The stability of Pt/C and PtCo/C with different initial particle sizes was monitored over 3000 potential cycles. The increase in particle size was fit to a linear trend as a function of cycles. The most stable electrocatalyst was found to be the alloyed PtCo with the larger initial particle size.
Highlights: • We have demonstrated AgI sensitized solar cell for the first time. • Obtained mesoporous titania powders possessed small crystallite size, high purity and surface area, and developed mesopores with a narrow pore size distribution. • Photovoltaic measurements revealed the electron injection from AgI to TiO{sub 2}. • The assembled AgI-QD solar cells yielded a power conversion efficiency of 0.64% under one sun illumination. • AgI may be a suitable candidate material for use as a non-toxic sensitizer in QDSSC. - Abstract: The present study reports the performance of a new photosensitizer -AgI quantum dots (QDs)- and mesoporous titania (TiO{sub 2}) nanocrystals synthesized by sol–gel (SG) method for solar cells. Furthermore, the effects of n-heptane on the textural properties of TiO{sub 2} nanocrystals were comprehensively investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N{sub 2} adsorption–desorption measurements, and UV–vis spectroscopy. TiO{sub 2} powders exhibited an anatase-type mesoporous structure with a high surface area of 89.7 m{sup 2}/g. Afterwards, the QDs were grown on mesoporous TiO{sub 2} surface to fabricate a TiO{sub 2}/AgI electrode by a successive ionic layer adsorption and reaction (SILAR) deposition route. Current–voltage characteristics and electrochemical impedance spectroscopy (EIS) data demonstrated that the injection of photoexcited electrons from AgI QDs into the TiO{sub 2} matrix produces photocurrents. The assembled AgI-QD solar cells yielded a power conversion efficiency of 0.64% and a short-circuit current of 2.13 mA/cm{sup 2} under one sun illumination.
A system and method for decoding an unknown automotive controller area network (“CAN”) message definitions. CAN data vehicle signal mappings are typically held in secret and varied by automotive model and year. Without knowledge of the mappings, the wealth of real-time vehicle data hidden in the automotive CAN packets is uninterpretable—impeding research, after-market tuning, efficiency and performance monitoring, fault diagnosis, and privacy-related technologies. This technology can ascertain the CAN signals' boundaries (start bit and length), endianness (byte ordering), signedness (binary-to-integer encoding) from raw CAN data. This allows conversion of CAN data to time series. Interpreting the translated CAN data's physical meaning and finding a linear mapping to standard units (e.g., knowing the signal is speed and scaling values to represent units of miles per hour) can be achieved for many signals by leveraging diagnostic standards to obtain real-time measurements of in-vehicle systems. The system and method can be integrated into lightweight hardware enabling an OBD-II plugin for real-time in-vehicle CAN decoding or run on standard computers. The system can output a standard DBC file with the signal definition information.
We are grateful for the Department of Energy for support of this research related to the improvement of power conversion efficiency of organic photovoltaic architectures over the years. As we noted at the beginning and now, the fundamental photophysical pathways that connect the absorption of light to the production of charge carriers remain elusive in spite of continuing experimental and theoretical efforts. Our investigations were directed toward gaining information about the mechanism of this ultrafast, long-range charge separation in photovoltaic systems with non-fullerene acceptors. This problem is still of high importance for the organic photovoltaics because solving this problem will allow us to minimize the contribution of the geminate recombination and trapping the charges in bound charge transfer states. Extremely low charge separation driving energy specific to non-fullerene acceptor systems reduces the energy loss in organic photovoltaic cells making them competitive with inorganic and perovskite photovoltaic systems. A major accomplishment of this study was to detail the long-range ballistic charge separation in donor-non-fullerene acceptor photovoltaic systems. We have successfully probed the spatial structure of ultrafast long-range (~40nm) ballistic charge separation in donor-non-fullerene acceptor photovoltaic system. We performed a systematic investigation of the delocalized states in their connection to the efficient long-range charge separation using the pulse pair interferometric near-field microscopy method. This method possesses unique capability of detecting coherent effects with spatial resolution of few tens of nanometers. These measurements allowed us the determination of delocalized excitations locally in a thin film photovoltaic system and to be connected to the long-range charge separation and the power conversion efficiency. We also investigated long-lived coupled triplet pairs in a singlet fission process for the possibility of concerted extraction of two electrons from triplet entangled states. New experimental and theoretical approaches of the concerted double electron extraction were carried out. The impact of this work is the development of important structure-property relationships to the design criteria of more efficient organic photovoltaic cells in accordance with the BES mission.
Highlights: • High-performance PANI/MWCNT-CE was incorporated in a Pt-CE in DSSCs. • GNS/MWCNT/PANI-CE exhibits a high power conversion efficiency (PCE) of 7.52%. • GNS/MWCNT/PANI composite has a high catalytic activity for the reduction of I{sub 3}{sup −}. • GNS/MWCNT/PANI composite has a low R{sub CT} on the electrolyte/CE interface. - Abstract: A graphene-based nanosheet composite/multiwalled carbon nanotube/polyaniline (GNS/MWCNT/PANI) was synthesized via an in situ polymerization technique and applied by the spin-coating method as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). The combination of the high catalytic activity of PANI and outstanding conductivity of GNS/MWCNT improved the photovoltaic performance of the hybrid CE. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the GNS/MWCNT/PANI composite has high catalytic activity for the reduction of triiodide to iodide and low charge-transfer resistance at the electrolyte/electrode interface. Transmission electron microscopy (TEM) images showed that the GNS/MWCNT/PANI-CE has a rough and porous structure and X-ray diffraction analysis confirmed the formation of PANI coating on the surface of the GNS/CNT. In particular, current–voltage measurements showed the superior power conversion efficiency (PCE) of 7.52% of the DSSC based on GNS/MWCNT/PANI-CE compared to the PCE of 6.69% of the DSSC based on Pt-CE.